Industrial workers often wear safety helmets or hats to protect themselves from falling objects, electrocution and bumping their heads. The helmets are designed to reduce or hopefully eliminate serious head injuries. To put the problem in proper perspective, it has been reported that there are an average of about 152,000 head injuries per year. Furthermore, approximately eight percent of all accidental electrocutions are caused by the head making contact (directly or indirectly) with an electrical source.
In view of these dangers, various helmet standards have been established over the years to ensure the safety of the helmet wearing populace. See, for example, ANSI Z89.1-1969 entitled, "Safety Requirements for Industrial Head Protection" and ANSI Z89.2-1971 entitled, "Safety Requirements for Industrial Protective Helmets for Electrical Workers, Class B". Both of the aforementioned standards are published by the American National Standards Institute, Inc. These references, among others, set forth minimum guidelines for the manufacture of safety helmets.
Briefly, a safety helmet protects the wearer in various ways. Firstly, the shell deflects a blow to the head. A well designed hat will dissipate the blow over the entire surface of the shell. Should the force of the impact be great enough, the hat will shatter thereby reducing the kinetic energy of the moving object eventually reaching the worker's head. Moreover, the internal helmet suspension is designed to absorb a substantial portion of the blow. Secondly, an electrical safety hat must meet certain minimum requirements for dielectric strength and imperviousness to moisture. Such hats, obviously, must not act as conduits for electric current. Thirdly, by simply wearing a hat, a mechanical barrier is set up between the head and the environment. In this fashion, the deleterious effects of acid spills, hot liquid spills and airborne contaminants are substantially reduced.
Of all the aforementioned uses of a safety hat, probably its most important function is energy attenuation. It goes without saying that the greater the ability of a helmet to deflect and absorb an impact, the safer the hat. Since the energy characteristics of a shell are more or less determined by the elastic properties of the shell material, there is relatively little a helmet designer may do to improve the shock absorbing characteristics of the shell itself. Accordingly, it is the suspension system of a safety helmet that is the subject of this disclosure.
Present day suspension systems basically consist of a plurality of interconnecting straps forming a webbed, head-circumscribing structure within the helmet. The webbing is, in turn, attached to the helmet by a series of fixed mounts, usually imbedded within the shell itself. A headband (usually adjustable) is affixed to the webbing in a known manner. Any shock transmitted from the shell to the suspension system is partially alleviated by the elastic nature of the webbing. However, it is still very possible that an undesirably high amount of force will be transmitted to the head. Accordingly, it is very important that a minimum clearance be maintained between the shell and the webbing to accommodate the shock of a blow. The problem with present day designs is that by using fixed suspension mounting systems, a substantial portion of the blow is still physically transmitted directly to the wearer's head. The kinetic energy engendered by the blow is not effectively reduced since the fixed mount is not designed to absorb the impact. Indeed, a fixed mount may act as a direct transmitter of the shock to the head.
Clearly, an improved suspension system that absorbs a portion of the blow is desirable.